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Lu L.,Chongqing University | Li D.,Chongqing University | Li D.,Key Laboratory for Coal Mine Disaster Dynamics and Control | Yu L.,Chongqing University
Applied Mechanics and Materials | Year: 2011

Many different methods were found to increase the leaching rate by the researchers.In this paper,one of the methods-intensified leaching-was showed that the device for bioleaching was under the condition of static magnetic field. the device were designed according to Helmholtz coils,which can offered the static magnetic field,the leaching will start at the condition of the static magnetic field by the Thiobacillus ferrooxidans ( T. f ).the content of metals in samples were detected by Atomic fluorescence spectrometer after 25 days. Through the experimental analysis, the results showed that under the conditions of pulp density 5%,inoculum 10%,pH 2.0, magnetic induction intensity 3.14mT, the leaching rate of Cu and Fe in chalcopyrite mineral processing solid waste got improved. Especially the copper, the leaching rate raised from15.76% to 18.88%. © (2011) Trans Tech Publications. Source


Yang K.,Chongqing University | Li D.,Chongqing University | Li D.,Key Laboratory for Coal Mine Disaster Dynamics and Control
Research Journal of Chemistry and Environment | Year: 2011

Because of the high content of heavy metal in the fly ash from the burning system of the solid waste, the heavy metal can leach into the environment under natural conditions. Some technology must be adopted to improve the environmental pollution. Electrokinetic removal is a new kind of technology and it is paid high attention in many countries. This work shows the laboratory results of electrodialytic removal experiments about the fly ash from municipal solid waste in Chongqing. Two main mechanism of electrokinetic removal of heavy metal from the fly ash can be concluded: 1. heavy metal extracted from the fly ash; 2. the migration and enrichment of the metal ions. The electrolyte solution pH, electric current, electrical conductivity, voltage gradient were discussed to prove the removal effect in this experiment. The pH value changed smoothly in the cathode compartment, while it changed abruptly in the first 6 hours, but it changed smoothly in the rest time. The electrical current increased in the first 50 hours, then gradually decreased in the rest time. The resistance in the removal process would become bigger while the electric current will decrease. The electrical conductivity in the anode compartment increased while the electrical conductivity decreased in the cathode compartment. The electrical conductivity in anode and cathode electrolyte solution is highly related to the concentration of mobile ions. The metal hydroxide precipitation was the most serious factor that influenced the removal rate. From the experimental data, it can be seen that the content of Pb, Zn, Cd, As reduced to a certain level after the experiment, but a large proportion of heavy metal was not eliminated. Some enhanced measures should be taken during the experiment. Source


Li D.,Chongqing University | Li D.,Key Laboratory for Coal Mine Disaster Dynamics and Control | Yang K.,Chongqing University | Fan M.,Chongqing University
Research Journal of Chemistry and Environment | Year: 2013

Heavy metal pollution has become one of the most serious environmental problems in the world today. Due to the persistence and recalcitrance in the environment, the treatment of heavy metals is of special concern. In recent years, various methods for the removal of heavy metal from soil, waste water have been extensively studied. This paper has reviewed the current methods that have been used to control and removal heavy metals from the polluted soil, wastewater and some other substances. These technologies include chemical remediation, physics remediation and bioremediation. The chemical remediation methods include drip washing method, consolidation and stabilization method and ameliorant method. The ameliorant method is considered as the best method in the chemical remediation. The physics remediation methods include the revising soil method, microwave heat remediation method and the electrokinetic remediation method. Electrokinetic remediation method is one of the newest methods in the world. The bioremediation methods include the plant remediation, the animal remediation and the microorganism remediation. The plant remediation methods contain the plant extract, the plant volatilization and the plant stabilization. It is considered that the plant remediation is widely adopted for removal of the heavy metals from the soil and the microorganism remediation method is the hotspot in all the control and remediationchnology. Source


Li Y.,Chongqing University | Peng X.,Chongqing University | Li D.,Chongqing University | Li D.,Key Laboratory for Coal Mine Disaster Dynamics and Control | And 2 more authors.
Applied Mechanics and Materials | Year: 2011

MSWI fly ash is regulated as hazardous waste in many countries as it enriches heavy metals and many toxic components and these components would potentially leach when the ashes are land filled. In this study, the basic characteristic of fly ash was ananlysised. The result of XRF showed that the main elements in fly ash were Cl, Ca, K, Na, S, O, C, Si, Al, where Zn, Pb, Cr, Cu were the main heavy metals. The SEM analysis showed that the fly ash mainly formed with amorphous structure and was polymerized by many tiny structures. What's more, after electrokinetic removal experiment, extraction toxicity tests was carried out to investigate the environmental toxicity of the MSWI fly ash. It was determined that the original the extraction quantity of heavy metals was obviously higher than the "standard for pollution control on the landfill site of municipal solid waste" and the electrokinetic removal technology showed the effect on reducing the extraction quantity. However, some sample still could not reach the standard, further work should be done to improve it. © (2011) Trans Tech Publications. Source


Li D.,Chongqing University | Li D.,Key Laboratory for Coal Mine Disaster Dynamics and Control | Huang T.,Chongqing University | Huang T.,Key Laboratory for Coal Mine Disaster Dynamics and Control
Asian Journal of Chemistry | Year: 2014

This paper systematically expounds the fundamental characteristics of trace elements (zinc, lead, arsenic) in the coal samples, including content, occurrence, phases, microstructure, morphology and melting properties by the analysis of AFS, XRD, SEM-EDX and TG-DSC. It also discusses the thermodynamic behaviour and the mechanisms of migration and transformation on the basis of the experimental phenomena and the analyzed information. The capture efficiencies of the modified Ca-based sorbents (MCS) for Zn, Pb, As were studied comparative to the experimental results of calcium carbonate. The content of Zn, Pb and As in the coal samples were nearly all exceeding the standard values. Zn and Pb occurred mainly in the form of exchangeable, bound-sulfide and residue in the coal samples and more than 50 % of As was bound-sulfide. Zn, Pb and As in the most coal samples evaporated and gasified following the priority of As > Zn > Pb during the process of coal static combustion experiment. The lowest volatilization rate of Zn, Pb and As with the addition of modified Ca-based sorbents were18.81, 14.44 and 26.13%, respectively under the optimal experimental condition, which were much lower than the ratio with calcium carbonate under the same experimental condition. The surface area, pore diameter and porosity of calcium carbonate modified by Al2(SO4)3were obviously improved, some γ-Al2O3was found on the surface of the particle and the melting temperature of the coal mixed with modified Ca-based sorbent was high. Source

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